JP6836165B2 - Printing equipment and printing method - Google Patents

Description

The present invention relates to a technique for a recording head having a plurality of nozzle rows.

In an inkjet printer, for example, a plurality of nozzles arranged in a predetermined nozzle arrangement direction and an object to be printed are relatively moved in a relative movement direction intersecting the nozzle arrangement direction, and ink droplets are ejected from the nozzles according to the recorded data to form an object to be printed. Form dots. Further, since printing is performed at a high speed, a line printer is also known in which a printed matter is conveyed to form a printed image without moving nozzles arranged over almost the entire width direction intersecting the conveyed direction of the printed matter. Since the nozzles are arranged over almost the entire width direction of the printed matter, some line printers include a recording head in which a plurality of head chips having a nozzle row are combined.

For example, when combining a plurality of head chips in which C (cyan), M (magenta), Y (yellow), and K (black) nozzle rows are arranged in the transport direction, the recording head has at least two in the transport direction. It is necessary to line up the head chips for the minute. If each head chip has four rows of nozzles in the transport direction, the recording head becomes long in the transport direction, the landing position of the ink droplets tends to vary, and the printed matter easily comes into contact with the head chip. Therefore, for example, in each head chip, the nozzle row of C and the nozzle row of Y are arranged in the nozzle arrangement direction, the nozzle arrangement of M and the nozzle arrangement of K are arranged in the nozzle arrangement direction, and the nozzle arrangement is in the transport direction. Can be considered in two rows.
In the head body shown in Patent Document 1, the nozzle row of C and the nozzle row of Y are arranged in the nozzle arrangement direction, and the nozzle arrangement of M and the nozzle arrangement of K are arranged in the nozzle arrangement direction.

Japanese Unexamined Patent Publication No. 2015-131447

When arranging a plurality of nozzle rows in the nozzle arrangement direction in each head chip to reduce the number of nozzle rows in the transport direction, among the plurality of nozzle rows that eject ink droplets on the same line along the transport direction, the transport direction The distance between the nozzle rows of different colors in the above may differ depending on the position in the nozzle arrangement direction. In this case, it was found that streaks and color unevenness along the transport direction may occur.
It should be noted that the above-mentioned problems also exist in devices other than line printers such as serial printers.

One of an object of the present invention is to provide a technique capable of suppressing color unevenness due to a plurality of distances between nozzle rows of different colors in the relative movement direction of the recording head.

In order to achieve one of the above objects, the present invention is a printing device in which the recording head and the printed matter move relative to each other in a relative moving direction different from the arrangement direction of the nozzles in the nozzle row.
The recording head has two or more first nozzle rows that eject ink droplets of the first color, two or more second nozzle rows that eject ink droplets of the second color, and ink droplets of the third color. Has two or more third nozzle rows to eject
Of a plurality of nozzle rows that eject ink droplets on the same line along the relative movement direction,
The distance between the first nozzle row and the second nozzle row in the relative moving direction is constant.
There are a plurality of distances between the first nozzle row and the third nozzle row in the relative movement direction.
Regarding the upper limit of the amount of ink that can be ejected per unit area of the printed matter, the upper limit of the amount of ink obtained by combining the first nozzle row and the third nozzle row is the first nozzle row and the second nozzle row. It has an embodiment in which the first printing is performed, which is lower than the upper limit of the amount of ink combined with the nozzle row.

Further, the present invention is a printing method in which the recording head and the printed matter move relative to each other in a relative moving direction different from the direction in which the nozzles of the nozzle row are arranged.
The recording head has two or more first nozzle rows that eject ink droplets of the first color, two or more second nozzle rows that eject ink droplets of the second color, and ink droplets of the third color. Has two or more third nozzle rows to eject
Of a plurality of nozzle rows that eject ink droplets on the same line along the relative movement direction,
The distance between the first nozzle row and the second nozzle row in the relative moving direction is constant.
There are a plurality of distances between the first nozzle row and the third nozzle row in the relative movement direction.
Regarding the upper limit of the amount of ink that can be ejected per unit area of the printed matter, the upper limit of the amount of ink obtained by combining the first nozzle row and the third nozzle row is the first nozzle row and the second nozzle row. It has an embodiment in which the first printing is performed, which is lower than the upper limit of the amount of ink combined with the nozzle row.

The above-described aspect can provide a technique capable of suppressing color unevenness due to a plurality of distances between nozzle rows of different colors in the relative movement direction of the recording head.

The figure which shows the structural example of the printing apparatus schematically. The figure which schematically exemplifies the main part of the line printer as an inkjet printer. The figure which shows the example of a head tip schematically. The figure which shows the structural example of the color conversion lookup table schematically. The figure which shows typically the example of the ink amount upper limit of a secondary color. The flowchart which shows the example of the printed matter type selection process. A flowchart showing an example of a selective printing process using a color conversion lookup table according to the type of printed matter. A flowchart showing an example of a selective printing process using a color conversion lookup table according to a temperature condition. A flowchart showing an example of a selective printing process using a color conversion lookup table according to humidity conditions. FIG. 5 is a diagram schematically showing an example of color unevenness due to a plurality of distances between nozzle rows of different colors in the relative movement direction of the recording head in the comparative example. FIG. 11A schematically illustrates the state of ejected ink droplets when the distance between nozzle rows is relatively short, and FIG. 11B schematically illustrates the state of ejected ink droplets when the distance between nozzle rows is relatively long. Figure.

Hereinafter, embodiments of the present invention will be described. Of course, the following embodiments merely exemplify the present invention, and not all of the features shown in the embodiments are essential for the means for solving the invention.

(1) Outline of the technique included in the present invention:
First, an outline of the technique included in the present invention will be described with reference to the examples shown in FIGS. It should be noted that the figures of the present application are diagrams schematically showing examples, and the enlargement ratios in each direction shown in these figures may be different, and the figures may not be consistent. Of course, each element of the present technology is not limited to the specific example indicated by the reference numeral.

[Aspect 1]
The printing device 1 according to one aspect of the present technology is a printing device 1 in which the recording head 60 and the printed matter ME1 move relative to each other in a relative moving direction D2 different from the alignment direction D1 of the nozzles 64 in the nozzle row 68. The recording head 60 has two or more first nozzle rows NL1 that eject ink droplets 67 of the first color (for example, C), and two or more second nozzles that eject ink droplets 67 of the second color (for example, M). It has a nozzle row NL2 and two or more third nozzle rows NL3 for ejecting ink droplets 67 of a third color (for example, Y). Of the plurality of nozzle rows 68 that eject ink droplets 67 on the same line DL along the relative movement direction D2, the distance between the first nozzle row NL1 and the second nozzle row NL2 in the relative movement direction D2 ( For example, L0) is constant, and there are a plurality of distances (for example, L1 and L2) in the distance between the first nozzle row NL1 and the third nozzle row NL3 in the relative movement direction D2. The printing apparatus 1 has an ink amount upper limit that is a combination of the first nozzle row NL1 and the third nozzle row NL3 with respect to the upper limit of the ink amount that can be ejected per unit area of the printed matter ME1. For example, the first printing in which Dg) is lower than the upper limit of the amount of ink (for example, Db) in which the first nozzle row NL1 and the second nozzle row NL2 are combined is performed.

When the distance between the first nozzle row NL1 and the third nozzle row NL3 is relatively long on the same line DL along the relative movement direction D2, the time required for the ink droplet 67 from each nozzle row 68 to land on the printed matter ME1. Since the difference is relatively large, the ink droplet 67 that has landed earlier tends to dry. Therefore, the ink droplets 67 from each nozzle row 68 are difficult to mix and bleed. On the other hand, when the distance between the first nozzle row NL1 and the third nozzle row NL3 is relatively short on the same line DL along the relative movement direction D2, the ink droplets 67 from each nozzle row 68 land on the printed matter ME1. Since the time difference is relatively small, the ink droplet 67 that landed earlier is difficult to dry. Therefore, the ink droplets 67 from each nozzle row 68 are easily mixed in a liquid state and easily bleed. When the ink droplets 67 from each nozzle row 68 are mixed in a liquid state, the color development of dots due to the ink droplets is reduced as compared with the case where the distance between the first nozzle row NL1 and the third nozzle row NL3 is relatively long.

FIG. 10 schematically shows an example of color unevenness due to a plurality of distances between nozzle rows of different colors in the relative moving direction D2 of the recording head 60 in the comparative example. In FIG. 10, the recording head 60 is shown from the side opposite to the nozzle surface where the nozzle 64 is located, but for convenience, the position of the nozzle 64 is shown, and a nozzle for ejecting ink droplets of C, M, Y, or K is shown. The pattern is different for each color of ink droplets.
The recording head 60 shown in FIG. 10 includes a plurality of head tips 61 having nozzle rows 68C of C, nozzle rows 68M of M, nozzle rows 68Y of Y, and nozzle rows 68K of K. Here, the nozzle rows 68C and 68M are arranged in the relative movement direction D2, the nozzle rows 68Y and 68K are arranged in the relative movement direction D2, the nozzle rows 68C and 68Y are arranged in the arrangement direction D1 and the nozzle rows 68M and 68K are arranged. They are arranged in the arrangement direction D1. In order to realize high resolution of the printed image, the interval between the nozzles 64 of each nozzle row 68 is narrowed, but since it is necessary to form an ink flow path for each color, the head chip 61 has the nozzle 64 arrangement direction D1. It is assumed that non-ejection areas A1 and A2 without nozzles are generated in. In this case, in order to arrange the CMYK (cyan, magenta, yellow, and black) nozzles 64 on the same line DL, it is necessary to arrange at least three head tips 61 in the relative moving direction D2.

As shown in FIG. 10, the distance L0 of the nozzle rows 68C and 68M in the relative moving direction D2 is constant. On the other hand, the distances of the nozzle rows 68C and 68Y in the relative moving direction D2 have a plurality of distances L1 and L2, and the distances of the nozzle rows 68M and 68Y in the relative moving direction D2 also have a plurality of distances. For example, the distance between the nozzle rows 68C and 68Y on the lines DL1 and DL3 is L1, and the distance between the nozzle rows 68C and 68Y on the line DL2 is L2 (L2> L1). Further, the distance between the nozzle rows 68C and 68Y in the lines DL4 and DL6 is L1, but the ejection order of the ink droplets is opposite to that in the case of the lines DL1 and DL3, and the distance between the nozzle rows 68C and 68Y in the line DL5 is L2. Is the reverse of the case where the ink droplet ejection order is line DL2. The print areas AL1, AL2, AL3, AL4, AL5, AL6 pass through the lines DL1, DL2, DL3, DL4, DL5, DL6, respectively, and are the same as the lines DL1, DL2, DL3, DL4, DL5, DL6. This is the print area that serves as the ink droplet ejection timing.

FIG. 11A schematically illustrates the state of ink droplets 67C, 67Y ejected from the nozzles 64C, 64Y of the nozzle rows 68C, 68Y in the line DL1 in which the distance between the nozzle rows is relatively short. In FIG. 11A, first, the ink droplet 67Y is ejected from the nozzle 64Y of Y, and when the printed matter ME1 moves in the paper feed direction D21 by a relatively short distance L1, the ink droplet 67C is ejected from the nozzle 64C of C. In this case, a part of the preceding ink droplet 67Y is liquid, and when the subsequent liquid ink droplet 67C overlaps with the liquid ink droplet 67Y, the ink droplets 67C and 67Y are mixed in the liquid state, and blurred dots are formed. It is formed and the color development is reduced.

FIG. 11B schematically illustrates the state of the ink droplets 67C and 67Y ejected from the nozzles 64C and 64Y in the line DL2 in which the distance between the nozzle rows is relatively long. In FIG. 11B, first, the ink droplet 67Y is ejected from the nozzle 64Y, and when the printed matter ME1 moves in the paper feed direction D21 by a relatively long distance L2, the ink droplet 67C is ejected from the nozzle 64C. In this case, even if the preceding ink droplet 67Y dries and the subsequent liquid ink droplet 67C overlaps this portion, the ink droplets 67C and 67Y do not mix and the formed dots do not blur, as compared with the case of the line DL1. High color development.

From the above, as shown in FIG. 10, the color development may differ between the adjacent print areas of the print areas AL1 to AL6, and streaks and color unevenness along the relative movement direction D2 occur in the printed image.

In the above aspect 1 of the present technology, when the first nozzle row NL1 and the third nozzle row NL3 eject ink droplets 67 on the same line DL along the relative movement direction D2, the ink amount upper limit (Dg) is lowered. There is. As a result, the difference in color development due to the difference in the distance between the first nozzle row NL1 and the third nozzle row NL3 in the relative movement direction D2 is suppressed, and the color unevenness is suppressed. On the other hand, when the first nozzle row NL1 and the second nozzle row NL2 eject ink droplets 67 on the same line DL along the relative movement direction D2, the distance between the first nozzle row NL1 and the second nozzle row NL2. Since L0 is constant, color unevenness does not occur even if the upper limit of the amount of ink (Db) is maintained. If the upper limit of the ink amount (Db) is lowered to this case, the color reproduction range becomes narrower as a whole, but by maintaining the upper limit of the ink amount (Db) of the first nozzle row NL1 and the second nozzle row NL2. Color reproducibility is ensured.
From the above, the above aspect 1 can provide a printing apparatus capable of suppressing color unevenness due to a plurality of distances between nozzle rows of different colors in the relative moving direction of the recording head.

Here, the nozzle is a small hole on which ink droplets are ejected. The ink droplets also include non-colored inks such as ink droplets that improve image quality.
The relative movement of the recording head and the printed matter means that the printed matter moves without moving the recording head, the recording head moves without moving the printed matter, and both the recording head and the printed matter move. Includes moving.
The appendix of the above aspect 1 is the same as that of the following aspects.

[Aspect 2] (exemplified in FIG. 2 and the like)
The recording head 60 may include a plurality of head tips 61 having the first nozzle row NL1, the second nozzle row NL2, and the third nozzle row NL3. In the head tip 61, the first nozzle row NL1 and the second nozzle row NL2 are arranged in the relative movement direction D2, and one of the first nozzle row NL1 and the second nozzle row NL2 and the third The nozzle row NL3 and the nozzle row NL3 may be arranged in the arrangement direction D1. In this embodiment, since the length La of the recording head 60 in the relative moving direction D2 can be shortened, the landing position of the ink droplet 67 is less likely to vary, and the printed matter is less likely to come into contact with the head chip.

[Aspect 3] (exemplified in FIG. 2 and the like)
In the head chip 61, the third nozzle row NL3 and the fourth nozzle row NL4 for ejecting ink droplets 67 of a fourth color (for example, K) may be arranged in the relative moving direction D2. This aspect can provide an example in which color unevenness due to a plurality of distances between nozzle rows of different colors in the relative movement direction of the recording head can be suppressed.

[Aspect 4] (exemplified in FIG. 2 and the like)
The length La of the recording head 60 in the relative moving direction D2 may be three times the length Lb of the head chip 61 in the relative moving direction D2. In this embodiment, since the length La of the recording head 60 in the relative moving direction D2 can be minimized, the landing position of the ink droplet 67 is less likely to vary, and the printed matter is less likely to come into contact with the head chip. ..

[Aspect 5] (exemplified in FIG. 2 and the like)
The first color, the second color, and the third color may be selected from cyan, magenta, and yellow. This example can provide a suitable example of suppressing color unevenness due to a plurality of distances between nozzle rows of different colors in the relative movement direction of the recording head.

[Aspect 6] (exemplified in FIG. 7 and the like)
In the printing device 1, the ink amount upper limit (for example, Dg) of the first printing, the first nozzle row NL1 and the third nozzle row NL3 is the first nozzle row NL1 and the second nozzle row NL1. A selective printing unit U1 that selectively performs a plurality of printing including a second printing with an ink amount upper limit (for example, Db) including NL2 may be provided. Since this aspect allows selection to improve color reproducibility, it provides a suitable example of suppressing color unevenness due to a plurality of distances between nozzle rows of different colors in the relative movement direction of the recording head. can do.
Although not included in the above aspect 6, the case where the printing apparatus does not perform the second printing is also included in the present technology.

[Aspect 7] (exemplified in FIG. 6)
The printing device 1 may include a printed matter type selection unit U2 that accepts selection of the type of printed matter ME1 used for printing. The selective printing unit U1 may perform the first printing when the type of the printed matter ME1 that has received the selection is the first type. The selective printing unit U1 may perform the second printing when the type of the printed matter ME1 that has received the selection is the second type. In this aspect, the color reproducibility can be improved when the type of the printed matter is the second type.

[Aspect 8] (exemplified in FIG. 8 and the like)
The printing device 1 may include a temperature sensor SE1 that detects the temperature T. The selective printing unit U1 may perform the first printing when the temperature T detected by the temperature sensor SE1 satisfies the first temperature condition (for example, less than the temperature Tt). The selective printing unit U1 performs the second printing when the temperature T detected by the temperature sensor SE1 satisfies the second temperature condition (for example, the temperature Tt or more) higher than the first temperature condition. May be good. This aspect can improve the color reproducibility when the second temperature condition is higher than the first temperature condition.

[Aspect 9] (exemplified in FIG. 9 and the like)
The printing device 1 may include a humidity sensor SE2 that detects humidity H. The selective printing unit U1 may perform the first printing when the humidity H detected by the humidity sensor SE2 satisfies the first humidity condition (for example, humidity Ht or more). The selective printing unit U1 performs the second printing when the humidity H detected by the humidity sensor SE2 satisfies the second humidity condition (for example, less than the humidity Ht) lower than the first humidity condition. May be good. This aspect can improve the color reproducibility when the second humidity condition is lower than the first humidity condition.

[Aspect 10] (exemplified in FIGS. 7 to 9 and the like)
When performing the first printing, the selective printing unit U1 combined the first nozzle row NL1 and the third nozzle row NL3 according to the first correspondence relationship (for example, color conversion lookup table LUT1) from the input color. Even if the output color is converted so that the ink amount upper limit (for example, Dg) is lower than the ink amount upper limit (for example, Db) of the first nozzle row NL1 and the second nozzle row NL2 combined. Good. When performing the second printing, the selective printing unit U1 combined the first nozzle row NL1 and the third nozzle row NL3 according to a second correspondence relationship (for example, a color conversion lookup table LUT2) from the input color. The upper limit of the amount of ink (for example, Dg) may be converted to the output color in which the ink is used so that the upper limit of the amount of ink (for example, Db) is the sum of the first nozzle row NL1 and the second nozzle row NL2. This aspect can provide a suitable example of suppressing color unevenness due to a plurality of distances between nozzle rows of different colors in the relative movement direction of the recording head.

[Aspect 11]
By the way, the printing method according to one aspect of the present technology includes a step corresponding to the above-mentioned printing apparatus 1. This aspect can provide a printing method capable of suppressing color unevenness due to a plurality of distances between nozzle rows of different colors in the relative movement direction of the recording head.

Further, the present technology is applied to a composite device including the printing device, a control method of the composite device, a control program of the printing device, a control program of the composite device, a computer-readable medium on which the control program is recorded, and the like. It is possible. The device described above may be composed of a plurality of distributed parts.

(2) Specific example of a printing device including an image processing device:
FIG. 1 schematically shows a configuration example of a printing device including an image processing device. The printing device 1 shown in FIG. 1 is represented as a printing system (printing device in a broad sense) including components of the present technology, includes at least an inkjet printer 2 in a narrow sense as a sales unit, and may include a host device 100 and the like. It shall be. FIG. 1 also shows a configuration example of a line printer as the inkjet printer 2. The printing apparatus to which the present technology can be applied may include a copier, a facsimile, a multifunction device having these functions, and the like. Inks used in an inkjet printer that forms a color image include, for example, C (cyan), M (magenta), Y (yellow), and K (black) inks. Of course, the ink also includes Lc (light cyan), Lm (light magenta), Dy (dark yellow), Lk (light black), R (red), Or (orange), Gr (green), and for improving image quality. Non-colored ink, etc. may be included.

FIG. 2 schematically illustrates a main part of a line printer as an inkjet printer 2. FIG. 3 schematically illustrates one of the head tips 61. In FIGS. 2 and 3, the recording head 60 is shown from the side opposite to the nozzle surface where the nozzle 64 is located, but for convenience, the position of the nozzle 64 is shown and ink droplets 67 of C, M, Y, or K are ejected. The nozzles to be used are represented by color-coded patterns of ink droplets 67.
The line printer has a line head which is a recording head 60 in which a plurality of head chips 61 are combined, and when the ink droplet 67 is ejected to form the dot DT0, the recording head 60 does not move and the long printed matter ME1 is formed. Moving. A printed matter (print substrate) is a material that holds a printed image, and at least all types of paper / paperboard and processed products described in JIS (Japanese Industrial Standards) P0001: 1998 (paper / paperboard and pulp terms). including. Resin sheets, metal plates, three-dimensional objects, etc. are also included in the printed matter.

In FIG. 2, reference numeral D1 is an arrangement direction of nozzles 64, reference numeral D2 is a relative movement direction between the recording head 60 and the printed matter ME1, reference numeral D21 is a paper feed direction, and reference numeral D3 is a width direction of a long printed matter ME1. Shown. The relative moving direction D2 is also referred to as a scanning direction. When the printed matter ME1 moves from the upstream side in the transport direction to the downstream side in the transport direction with respect to the fixed recording head 60, dots DT0 are formed in order with respect to the printed matter ME1 from the downstream side in the transport direction to the upstream side in the transport direction. .. In the example of FIG. 2, the arrangement direction D1 and the width direction D3 are the same, but the arrangement direction D1 and the width direction D3 may be deviated by approximately 45 ° or the like. These directions D1 and D3 and the paper feed direction D21 (relative movement direction D2) may be different directions, and not only are they orthogonal to each other, but also when they intersect at approximately 45 ° and are not orthogonal to each other. include. Of course, the intersection of two directions means that the two directions are out of alignment, including being orthogonal. The recording head 60 and the dot DT0 shown in FIGS. 2 and 3 are schematically shown for the sake of explanation, and the actual size, shape, number, and the like are not always as shown in these figures. For example, the number of head chips 61 included in the recording head 60 is not limited to 6 as shown in FIG. 2, and may be 5 or less, or 7 or more. The number of nozzle rows 68 included in the head tip 61 is not limited to four rows, and may be three rows or less, or five or more rows. The number of nozzles included in the nozzle row 68 is not limited to 10, and is usually 11 or more, but may be 9 or less.

The recording head 60 shown in FIG. 2 includes nozzle row 68C of C (example of first nozzle row NL1), nozzle row 68M of M (example of second nozzle row NL2), and nozzle row 68Y of Y (example of third nozzle row NL3). Example), and a plurality of head tips 61 having a nozzle row of K 68K (example of the fourth nozzle row NL4). Here, the nozzle rows 68C and 68M are arranged in the relative movement direction D2, the nozzle rows 68Y and 68K are arranged in the relative movement direction D2, the nozzle rows 68C and 68Y are arranged in the arrangement direction D1 and the nozzle rows 68M and 68K are arranged. They are arranged in the arrangement direction D1. Here, the nozzle row 68C is an example of the first nozzle row NL1, the nozzle row 68M is an example of the second nozzle row NL2, the nozzle row 68Y is an example of the third nozzle row NL3, and the nozzle row 68K is the example of the third nozzle row NL3. This is an example of a four-nozzle row NL4. The recording head 60 has a plurality of head chips 61a so that dots DT0 can be formed on the printed matter ME1 by ink droplets 67 ejected from the nozzles 64C, 64M, 64Y, 64K over the entire width direction D3 of the printed matter ME1. , 61b, 61c, 61a, 61b, 61c are arranged. Here, the head tips 61a to 61c are collectively referred to as the head tip 61, the nozzle rows 68C, 68M, 68Y, 68K are collectively referred to as the nozzle row 68, and the nozzles 64C, 64M, 64Y, 64K are collectively referred to as the nozzle 64.

Even if the nozzles are arranged in a staggered pattern, a plurality of nozzles are arranged in a predetermined arrangement direction different from the relative movement direction, for example, in two rows, which is included in the present technology. The alignment direction in this case means the alignment direction of the nozzles in each row in the staggered arrangement.

As shown in FIG. 3, a plurality of nozzles 64 are arranged in each nozzle row 68 at intervals of nozzle pitch Np in the arrangement direction D1. While the nozzle pitch Np is very small in order to realize high resolution of the printed image, it is necessary to form an ink flow path to the nozzle 64 in the head chip 61. Therefore, it is not easy to form nozzles 64 at both ends of the head tip 61 in the alignment direction D1 at intervals of nozzle pitch Np. When nozzles 64 having a nozzle pitch Np interval cannot be formed at both ends of the head tip 61, non-ejection regions A1 are generated at both ends of the head tip 61. Further, since it is necessary to form ink flow paths for each color in the alignment direction D1, it is not easy to form nozzles 64 between the nozzle rows 68C and 68M and the nozzle rows 68Y and 68K at intervals of nozzle pitch Np. Absent. If nozzles 64 with an interval of nozzle pitch Np cannot be formed between the nozzle rows 68C and 68M and the nozzle rows 68Y and 68K, a non-ejection region A2 is generated between them.

When non-ejection regions A1 and A2 without nozzles occur in the head tip 61 in the alignment direction D1, as shown in FIG. 2, in order to arrange the CMYK nozzles 64 on the same line DL, the head tip 61 is moved in the relative moving direction. It is necessary to line up at least 3 in D2. In this specific example, the length La of the recording head 60 in the relative moving direction D2 is three times the length Lb of the head chip 61 in the relative moving direction D2. As a result, the length La of the recording head 60 in the relative moving direction D2 becomes the shortest, the landing position of the ink droplet 67 is less likely to vary, and the printed matter ME1 is more difficult to come into contact with the head chip 61.

FIG. 2 shows that the ink droplet 67 from the recording head 60 forms a line DL of dots DT0 along the relative moving direction D2 on the printed matter ME1. As will be described later, in this specific example, color unevenness between print areas due to a plurality of distances between nozzle rows of different colors in the relative movement direction D2 is suppressed by setting an upper limit of the amount of ink for the secondary color. ing. The upper limit of the amount of ink is the upper limit of the amount of ink that can be ejected per unit area of the printed matter ME1.

First, the configuration of the printing apparatus 1 shown in FIG. 1 will be described. The inkjet printer 2 shown in FIG. 1 includes a controller 10, a RAM (Random Access Memory) 20, a non-volatile memory 30, a mechanism 50, interfaces (I / F) 71 and 72, an operation panel 73, and a temperature sensor that detects temperature T. It is equipped with SE1, a humidity sensor SE2 that detects humidity H, and the like. The controller 10, the RAM 20, the non-volatile memory 30, the I / F 71, 72, and the operation panel 73 can input / output information to each other. The temperature sensor SE1 and the humidity sensor SE2 are connected to the controller 10.

The controller 10 includes a CPU (Central Processing Unit) 11, a resolution conversion unit 41, a color conversion unit 42, a halftone processing unit 43, a signal transmission unit 44, and the like. In addition, at least a part of the functions of these processing units (41 to 44) may be realized in the host device 100. The controller 10 can be configured by a SoC (System on a Chip) or the like.
The CPU 11 is a device that mainly performs information processing and control in the inkjet printer 2.

The resolution conversion unit 41 converts the resolution of the image obtained from the host device 100, the memory card 90, or the like into a print resolution (for example, 720 × 720 dpi or 360 × 360 dpi). The above-mentioned obtained image is represented by, for example, RGB data in which each pixel has an integer value of 256 gradations of RGB (red, green, and blue). If the obtained image is not RGB data, the obtained image may be converted into RGB data.
The color conversion unit 42 is, for example, CMYK data in which input color data DA1 which is RGB data as a print resolution is used as an integer value of 256 gradations of CMYK (cyan, magenta, yellow, and black) in each pixel. Convert to output color data DA2. At that time, the color conversion unit 42 converts the input color data DA1 into the output color data DA2 with reference to the color conversion lookup table selected from the color conversion lookup tables LUT1, LUT2, .... Hereinafter, the color conversion look-up table LUT1 is also simply referred to as “LUT1”, and the color conversion look-up table LUT2 is also simply referred to as “LUT2”.

The halftone processing unit 43 performs predetermined halftone processing such as a dither method, an error diffusion method, or a density pattern method on the gradation value of each pixel constituting the output color data DA2, and the gradation number of the gradation value. Is reduced to generate recorded data DA3. The recorded data DA3 is data representing the dot formation status of each pixel corresponding to the printed image IM1, and can be, for example, binary data indicating the presence or absence of dot formation of each pixel. In addition, the recorded data DA3 is the third floor capable of dealing with dots of different sizes, such as 0 without dots, 1 for small dot formation, 2 for medium dot formation, and 4 value data corresponding to 3 for large dot formation. Multi-valued data above the key may be used.
The signal transmission unit 44 generates a drive signal SG corresponding to the voltage signal applied to the drive element 63 of the head chip 61 based on the recorded data DA3 and outputs the drive signal SG to the drive circuit 62. If necessary, the recorded data DA3 may be rearranged in the order in which dots are formed by the mechanism unit 50.

Each of the above parts 41 to 44 may be composed of an ASIC (Application Specific Integrated Circuit), and the data to be processed may be directly read from the RAM 20 or the processed data may be directly written to the RAM 20.

The mechanism unit 50 controlled by the controller 10 includes a paper feed mechanism 53 and the like. The paper feed mechanism 53 conveys the printed matter ME1 in the paper feed direction D21. The recording head 60 is equipped with, for example, a head chip 61 that ejects CMYK ink droplets 67. The head chip 61 includes a drive circuit 62, a drive element 63, and the like. The drive circuit 62 applies a voltage signal to the drive element 63 according to the drive signal SG input from the controller 10. As the drive element 63, a piezoelectric element that applies pressure to the ink 66 in the pressure chamber communicating with the nozzle 64, a drive element that generates bubbles in the pressure chamber by heat and ejects ink droplets 67 from the nozzle 64, and the like can be used. it can. Ink 66 is supplied from the ink cartridge 65 to the pressure chamber of the head chip 61. The combination of the ink cartridge 65 and the head chip 61 is provided in each of the CMYK, for example. The ink 66 in the pressure chamber is ejected as ink droplets 67 from the nozzle 64 toward the printed matter ME1 by the driving element 63, and dots DT0 of the ink droplets 67 are formed on the printed matter ME1 such as printing paper. A printed image IM1 with a plurality of dots DT0 is formed on the printed matter ME1.

The RAM 20 stores a program PRG2 or the like that enables the printing device 1 to perform functions such as the selective printing unit U1 and the printed matter type selection unit U2.
The non-volatile memory 30 stores program data PRG1 developed in the RAM 20, color conversion lookup tables LUT1, LUT2, ..., And the like. As the non-volatile memory 30, a magnetic recording medium such as a ROM (Read Only Memory), a flash memory, or a hard disk is used. Expanding the program data PRG1 means writing it to the RAM 20 as a program PRG2 that can be interpreted by the CPU 11.

The card I / F71 is a circuit for writing data to the memory card 90 and reading data from the memory card 90.
The communication I / F 72 is connected to the communication I / F 172 of the host device 100, and inputs / outputs information to / from the host device 100. A display device 174 or the like may be connected to the host device 100. The host device 100 includes a computer such as a personal computer (including a tablet terminal), a digital camera, a digital video camera, a mobile phone such as a smartphone, and the like.

The operation panel 73 includes an output unit 74, an input unit 75, and the like, and the user can input various instructions to the inkjet printer 2. The output unit 74 is composed of, for example, a liquid crystal panel (display unit) that displays information according to various instructions and information indicating the state of the inkjet printer 2. The output unit 74 may output these information by voice. The input unit 75 is composed of operation keys (operation input units) such as cursor keys and enter keys, for example. The input unit 75 may be a touch panel or the like that accepts operations on the display screen.
The mechanism unit 50 including the paper feed mechanism 53 and the head chip 61 will be referred to as a printing unit UR.

Next, a structural example of the color conversion lookup table will be described with reference to FIG. Since the structures of LUT1 and LUT2 are similar, the structures of LUT1 and LUT2 are schematically illustrated together in FIG. In LUT1 and LUT2, the coordinate values (Rj, Gj, Bj) and the CMYK color space (example of output color space CS2) in the RGB color space (example of input color space CS1) of the grid points GD0 for a plurality of lattice points GD0 are used. Correspondence with the coordinate values (Cj, Mj, Yj, Kj) of is defined. The variable j here is a variable that identifies the grid point GD0. Note that the grid point means a virtual point arranged in the input color space, and it is assumed that the output coordinate value corresponding to the position of the grid point in the input color space is stored in the grid point. I have to. The present technology includes not only a plurality of grid points being evenly arranged in the input color space, but also a plurality of grid points being unevenly arranged in the input color space. LUT1 and LUT2 shown in FIG. 4 have Ng grid points GD0 (Ng is an integer of 2 or more) for each of the R axis, the G axis, and the B axis. The number of lattice points Ng in the axial direction is not particularly limited, and may be 16, 32, 64, or the like.

Here, the coordinate value of each pixel PX1 of the input color data DA1 is (R1i, G1i, B1i), and the coordinate value of each pixel PX2 of the output color data DA2 is (C1i, M1i, Y1i, K1i). The variable j here is a variable that identifies the pixels PX1 and PX2. Each pixel PX1 of the input color data DA1 and each pixel PX2 of the output color data DA2 have a 1: 1 correspondence. FIG. 4 schematically shows the position of the point P1 in the RGB color space corresponding to the input coordinate values (R1i, G1i, B1i). The input coordinate values (R1i, G1i, B1i) are based on, for example, the grid point coordinate values (Rj, Gj, Bj) and the output coordinate values (Cj, Mj, Yj, Kj) of a plurality of grid points GD0 surrounding the point P1. Is converted into output coordinate values (C1i, M1i, Y1i, K1i). Known interpolation methods such as tetrahedral interpolation, hexahedral interpolation, and the like can be used for the calculation of this conversion.

By the way, when a recording head 60 including a plurality of head tips 61 having non-ejection regions A1 and A2 is used, the distance between the nozzle rows in the relative moving direction D2 is the print area depending on the combination of the nozzle rows 68C, 68M, 68Y, 68K. It may vary depending on.

As shown in FIG. 2, the distance L0 of the nozzle rows 68C and 68M in the relative moving direction D2 is constant. On the other hand, the distances of the nozzle rows 68C and 68Y in the relative moving direction D2 have a plurality of distances L1 and L2, and the distances of the nozzle rows 68M and 68Y in the relative moving direction D2 also have a plurality of distances. For example, the distance between the nozzle rows 68C and 68Y on the lines DL1 and DL3 is L1, and the distance between the nozzle rows 68C and 68Y on the line DL2 is L2 (L2> L1). Further, the distance between the nozzle rows 68C and 68Y in the lines DL4 and DL6 is L1, but the ejection order of the ink droplets is opposite to that in the case of the lines DL1 and DL3, and the distance between the nozzle rows 68C and 68Y in the line DL5 is L2. Is the reverse of the case where the ink droplet ejection order is line DL2. The print areas AL1, AL2, AL3, AL4, AL5 and AL6 are print areas having the same ink droplet ejection timing as the lines DL1, DL2, DL3, DL4, DL5 and DL6, respectively.

As shown in FIG. 11A, when the distance between the nozzle rows is relatively short, a part of the preceding ink droplets (67Y) that landed on the printed matter ME1 remains liquid, and the liquid ink droplets (67Y) become liquid. When the subsequent liquid ink droplets (67C) overlap, the ink droplets (67C, 67Y) are mixed in a liquid state, bleeding dots are formed, and the color development is deteriorated. On the other hand, as shown in FIG. 11B, when the distance between the nozzle rows is relatively long, the preceding ink droplet (67Y) that has landed on the object to be printed ME1 dries, and the trailing liquid ink droplet (67C) is formed in this portion. Even if the ink droplets 67C and 67Y are overlapped, the ink droplets 67C and 67Y are not mixed, the formed dots are not blurred, and the color development is higher than that in the case where the distance between the nozzle rows is relatively short. Therefore, assuming that the upper limit of the amount of ink for the secondary colors C and Y and the upper limit for the amount of ink for the secondary colors M and Y is the same as the upper limit for the amount of ink for the secondary colors C and M, the relative movement direction to the printed image is as shown in FIG. Streaks and color unevenness along D2 will occur.

Therefore, like the ink amount upper limit of LUT1 illustrated in FIG. 5, the ink amount upper limit Dg of the secondary colors of C and Y and the ink amount upper limit Dr of the secondary colors of M and Y are set to the secondary of C and M. By making the color ink amount lower than the upper limit Db, it is possible to suppress the occurrence of streaks and color unevenness along the relative movement direction D2 in the printed image.

Here, the ink color combination "C + M" represents the secondary color of C and M (corresponding to B (blue)), and the ink color combination "C + Y" represents the secondary color of C and Y (G (green)). Correspondence), and "M + Y" of the ink color combination represents the secondary color of M and Y (corresponding to R (red)). The “intercolor distance” means the distance between the nozzle rows corresponding to each color included in the ink color combination in the relative movement direction D2, and in the case of the ink color combination “C + M”, the distance between the nozzle rows 68C and 68M (L0). ), The ink color combination "C + Y" means the distance between the nozzle rows 68C and 68Y (L1, L2), and the ink color combination "M + Y" means the distance between the nozzle rows 68M and 68Y. To do. The ink amount upper limit Db means the upper limit of the ink usage amount which is the sum of the ink usage amount of C (corresponding to Cj) and the ink usage amount of M (Mj), and the nozzle row 68C (first nozzle row NL1) and the nozzle. This is the upper limit of the amount of ink combined with the row 68M (second nozzle row NL2). The ink amount upper limit Dg means the upper limit of the ink usage amount which is the sum of the ink usage amount of C (corresponding to Cj) and the ink usage amount of Y (Yj), and the nozzle row 68C (first nozzle row NL1) and the nozzle. This is the upper limit of the amount of ink combined with the row 68Y (third nozzle row NL3). The ink amount upper limit Dr means the upper limit of the ink usage amount which is the sum of the ink usage amount of M (corresponding to Mj) and the ink usage amount of Y (Yj), and the nozzle row 68M (second nozzle row NL2) and the nozzle. This is the upper limit of the amount of ink combined with the row 68Y (third nozzle row NL3).

LUT1 sets the upper limit of ink amount Dg and Dr (120% in FIG. 5) of secondary colors having different "intercolor distances" to the upper limit of ink amount Db of secondary colors having a constant "intercolor distance" (150 in FIG. 5). %) Is a color conversion lookup table lower than. LUT2 sets the upper limit of ink amount Dg and Dr (150% in FIG. 5) of secondary colors having different "intercolor distances" to the upper limit of ink amount Db of secondary colors having a constant "intercolor distance" (150 in FIG. 5). %) Is a color conversion lookup table. In LUT1 and LUT2, the ink amount upper limit Db is the maximum value of the sum of the ink usage amount Cj and the ink amount upper limit Mj, and the ink amount upper limit Dg is the maximum value of the sum of the ink usage amount Cj and the ink amount upper limit Yj. The amount upper limit Dr is the maximum value of the sum of the ink usage amount Mj and the ink amount upper limit Yj. "MAX" is a function representing the maximum value.

By using the above LUT1, when the nozzle row 68C and the nozzle row 68Y eject ink droplets 67 on the same line DL along the relative movement direction D2, the ink amount upper limit Dg is the secondary color of C and M. It is lower than the ink amount upper limit Db. As a result, the difference in color development due to the difference in the distances of the nozzle rows 68C and 68Y in the relative movement direction D2 is suppressed, and the color unevenness is suppressed. Further, when the nozzle row 68M and the nozzle row 68Y eject ink droplets 67 on the same line DL along the relative movement direction D2, the ink amount upper limit Dr is higher than the ink amount upper limit Db of the secondary colors C and M. Is also down. As a result, the difference in color development due to the difference in the distances of the nozzle rows 68M and 68Y in the relative movement direction D2 is suppressed, and the color unevenness is suppressed. On the other hand, when the nozzle row 68C and the nozzle row 68M eject the ink droplet 67 on the same line DL along the relative movement direction D2, the distance L0 between the nozzle row 68C and the nozzle row 68M is constant, so that the ink Color unevenness does not occur even if the upper limit Db of the amount is maintained. If the ink amount upper limit Db is lowered to this case, the color reproduction range is narrowed as a whole, but the color reproducibility is ensured by maintaining the ink amount upper limit Db in which the nozzle rows 68C and 68M are combined.
From the above, in this specific example, it is possible to suppress color unevenness due to a plurality of distances between nozzle rows of different colors in the relative movement direction of the recording head.

(3) Example of selectively using a color conversion lookup table:
However, lowering the upper limit of the amount of ink for some secondary colors also means that the color reproduction range for the secondary colors is narrowed. Therefore, when it is difficult for color unevenness to occur due to the difference in "color-to-color distance", the upper limit of the ink amount may not be lowered. For example, the printed matter includes a printed matter in which color unevenness is likely to occur due to a different "color-to-color distance" and a printed matter in which color unevenness is unlikely to occur due to a different "color-to-color distance". Therefore, when the type of the printed matter can be selected, the color conversion lookup table to be used may be switched according to the type of the printed matter.

FIG. 6 shows an example of the printed matter type selection process performed by the printing apparatus 1. FIG. 6 also shows a printed matter type selection screen 500. In this specific example, the inkjet printer 2 will be described as performing the printed matter type selection process, but the host device 100 may perform the printed matter type selection process, or the inkjet printer 2 and the host device 100 cooperate with each other. The printed matter type selection process may be performed. It is assumed that the printing device 1 can execute a plurality of processes in parallel by multitasking. The printed matter type selection process is started when a predetermined operation for setting the printed matter type is performed on the operation panel 73 or the host device 100. Here, the inkjet printer 2 that performs the printed matter type selection process corresponds to the printed matter type selection unit U2.

The process according to this embodiment is not limited to the example executed by the CPU, and may be executed by another electronic component [for example, an ASIC (Application Specific Integrated Circuit)]. Further, the process according to the present embodiment may be distributed by a plurality of CPUs, or may be executed by the CPU and the electronic component (for example, ASIC) operating in cooperation with each other.

When the process is started, the controller 10 of the inkjet printer 2 displays the printed matter type selection screen 500 for accepting the selection of the type of the printed matter ME1 used for printing on the output unit 74 of the operation panel 73 (step S102). The description of "step" is omitted below). On the printed matter type selection screen 500, a list of available types of printed matter ME1 is displayed, and selection of the type of printed matter ME1 to be used for printing is accepted from this list. For example, the type of printed matter that tends to cause color unevenness due to different "color-to-color distances" is "Media 1" (example of the first type), and color unevenness due to different "color-to-color distances" is unlikely to occur. It is assumed that the type of printed matter is "Media 2" (an example of the second type). The controller 10 receives an operation of selecting one from "Media 1", "Media 2", ... By the input unit 75.

When the selection of the type of the printed matter ME1 is accepted, the controller 10 stores the type of the printed matter ME1 that has received the selection in, for example, the non-volatile memory 30 (S104), and ends the printed matter type selection process. For example, when the selection of "Media 1" is accepted, the information representing "Media 1" is stored.

FIG. 7 shows an example of a selective printing process using a color conversion lookup table according to the type of the printed matter ME1. This process starts when an image is obtained from the host device 100, the memory card 90, or the like. Here, the inkjet printer 2 that performs the selective printing process corresponds to the selective printing unit U1. Further, S202 to S204, S206, S210 to S212 indicate a process in which the first printing is performed in which the ink amount upper limit Dg and Dr are lower than the ink amount upper limit Db. S202 to S204, S208, and S210 to S212 indicate a process in which the second printing is performed in which the ink amount upper limit Dg and Dr are set to the ink amount upper limit Db.

When the selective printing process is started, the controller 10 converts the resolution of the image obtained from the host device 100 or the like into the printing resolution by the resolution conversion unit 41 (S202). After the resolution conversion, the controller 10 branches the process according to the type of the printed matter ME1 (S204).

When "Media 1", which is prone to color unevenness due to different "color-to-color distances", is stored in the non-volatile memory 30, the controller 10 refers to the LUT 1 in the color conversion unit 42 and outputs the input color data DA1. Converted to color data DA2 (S206). The LUT1 is a color conversion for converting the input coordinate values (R1i, G1i, B1i) into the output coordinate values (C1i, M1i, Y1i, K1i) so that the ink amount upper limit Dg and Dr are lower than the ink amount upper limit Db. Look-up table. Therefore, the input color is converted into the output color in which the ink is used so that the ink amount upper limit Dg and Dr are lower than the ink amount upper limit Db according to LUT1.

When "Media 2", which is unlikely to cause color unevenness due to different "color-to-color distances", is stored in the non-volatile memory 30, the controller 10 refers to the LUT 2 in the color conversion unit 42 and outputs the input color data DA1. Converted to color data DA2 (S208). LUT2 is a color conversion lookup for converting input coordinate values (R1i, G1i, B1i) into output coordinate values (C1i, M1i, Y1i, K1i) so that the ink amount upper limit Dg and Dr become the ink amount upper limit Db. It is a table. Therefore, the input color is converted into the output color in which the ink is used so that the ink amount upper limit Dg and Dr become the ink amount upper limit Db according to LUT2.

When the selection of the type of printed matter (referred to as "Media 3") different from "Media 1" and "Media 2" is accepted, the controller 10 uses a color conversion lookup table different from LUT 1 and LUT 2. The input color data DA1 may be converted into the output color data DA2 with reference to.

After the output color data DA2 is generated, the controller 10 performs a predetermined halftone process on the output color data DA2 in the halftone processing unit 43 to reduce the number of gradations of the gradation value, and generates the recorded data DA3 ( S210). After the recorded data DA3 is generated, the controller 10 generates a drive signal SG based on the recorded data DA3 in the signal transmission unit 44, outputs the drive signal SG to the drive circuit 62, drives the mechanism unit 50 (S212), and performs selective printing processing. To end.

As described above, when the type of the printed matter ME1 whose selection is accepted is "Media 1", the first printing in which the ink amount upper limit Dg and Dr are lower than the ink amount upper limit Db is performed. Further, when the type of the printed matter ME1 for which the selection is accepted is "Media 2", the second printing is performed in which the ink amount upper limit Dg and Dr are the ink amount upper limit Db. Therefore, when the type of the printed matter ME1 is "Media 2", the upper limit of the amount of ink Dg and Dr does not decrease, so that the color reproducibility is improved. Of course, when the type of the printed matter ME 1 is "Media 1", color unevenness due to the difference in "color-to-color distance" is suppressed.

Further, when the environmental temperature of the inkjet printer 2 rises, the landed ink droplets tend to dry, so that it becomes difficult for ink droplets of different colors to mix with each other. On the other hand, when the ambient temperature of the inkjet printer 2 is lowered, the landed ink droplets are less likely to dry, so that the ink droplets of different colors are easily mixed in a liquid state, and the color development of the dots due to the ink droplets is reduced. Therefore, for example, when the inkjet printer 2 is provided with the temperature sensor SE1, the color conversion look-up table may be switched according to the detection temperature T of the temperature sensor SE1. The temperature sensor SE1 is preferably a temperature sensor that measures the ambient temperature, but may be a temperature sensor or the like that measures the temperature of the recording head 60.

FIG. 8 shows an example of a selective printing process using a color conversion lookup table according to temperature conditions. This process also starts when an image is obtained from the host device 100, the memory card 90, or the like. The inkjet printer 2 that performs this selective printing process also corresponds to the selective printing unit U1. S302 to S306, S308, S312 to S314 indicate a process in which the first printing is performed in which the ink amount upper limit Dg and Dr are lower than the ink amount upper limit Db. S302 to S306, S310, S312 to S314 indicate a process in which the second printing is performed in which the ink amount upper limit Dg and Dr are set to the ink amount upper limit Db.

When the selective printing process is started, the controller 10 converts the resolution of the image obtained from the host device 100 or the like into the printing resolution by the resolution conversion unit 41 (S302). Further, the controller 10 acquires the temperature T detected by the temperature sensor SE1 (S304) and branches the process according to the temperature condition (S306). For example, if the threshold value for the detected temperature T is Tt, it can be determined that the first temperature condition is satisfied if the temperature T is less than the threshold value Tt. It can be determined that the high second temperature condition is satisfied.

When T <Tt, which tends to cause color unevenness due to different "color-to-color distances", the controller 10 converts the input color data DA1 into the output color data DA2 by referring to the LUT 1 in the color conversion unit 42 (S308). .. On the other hand, when T ≧ Tt, which is unlikely to cause color unevenness due to the difference in “color-to-color distance”, the controller 10 converts the input color data DA1 into the output color data DA2 by referring to the LUT 2 in the color conversion unit 42 ( S310).

When a temperature condition different from the first temperature condition and the second temperature condition is satisfied, the controller 10 outputs the input color data DA1 with reference to the color conversion lookup table different from the LUT1 and the LUT2. It may be converted to DA2.

After the output color data DA2 is generated, the controller 10 converts the output color data DA2 into the recorded data DA3 in the halftone processing unit 43 (S312). After the recorded data DA3 is generated, the controller 10 generates a drive signal SG based on the recorded data DA3 in the signal transmission unit 44, outputs the drive signal SG to the drive circuit 62, drives the mechanism unit 50 (S314), and performs selective printing processing. To end.

As described above, the first printing in which the ink amount upper limit Dg and Dr are lower than the ink amount upper limit Db is performed under the first temperature condition in which color unevenness is likely to occur due to the difference in "color-to-color distance". Further, when the second temperature condition is such that color unevenness due to the difference in "color-to-color distance" is unlikely to occur, the second printing is performed in which the ink amount upper limit Dg and Dr are set to the ink amount upper limit Db. Therefore, when the second temperature condition is satisfied, the upper limit of the amount of ink Dg and Dr does not decrease, so that the color reproducibility is improved. Of course, when the first temperature condition is satisfied, color unevenness due to the difference in "intercolor distance" is suppressed.
When the selection of "Media 1", which is likely to cause color unevenness due to the difference in "color-to-color distance", is accepted, and the first temperature condition is such that color unevenness is likely to occur due to the difference in "color-to-color distance". The first printing may be performed on the surface, and the second printing may be performed in other cases. In addition, when the selection of "Media 1", which tends to cause color unevenness due to different "color-to-color distance", is accepted, or under the first temperature condition where color unevenness tends to occur due to different "color-to-color distance". The first printing may be performed in some cases, and the second printing may be performed in other cases.

Further, when the humidity of the environment of the inkjet printer 2 decreases, the landed ink droplets tend to dry, so that it becomes difficult for ink droplets of different colors to mix with each other. On the other hand, when the humidity of the environment of the inkjet printer 2 rises, it becomes difficult for the landed ink droplets to dry, so that the ink droplets of different colors are easily mixed in a liquid state, and the color development of the dots due to the ink droplets is reduced. Therefore, for example, when the inkjet printer 2 is provided with the humidity sensor SE2, the color conversion look-up table may be switched according to the detected humidity H of the humidity sensor SE2. The humidity sensor SE2 is preferably a humidity sensor that measures the humidity of the environment, but may be a humidity sensor or the like that measures the humidity of the recording head 60.

FIG. 9 shows an example of a selective printing process using a color conversion lookup table according to humidity conditions. This process also starts when an image is obtained from the host device 100, the memory card 90, or the like. The inkjet printer 2 that performs this selective printing process also corresponds to the selective printing unit U1. S402 to S406, S408, S421 to S414 indicate a process in which the first printing is performed in which the ink amount upper limit Dg and Dr are lower than the ink amount upper limit Db. S402 to S406, S410, S421 to S414 indicate a process in which the second printing is performed in which the ink amount upper limit Dg and Dr are set to the ink amount upper limit Db.

When the selective printing process is started, the controller 10 converts the resolution of the image obtained from the host device 100 or the like into the printing resolution by the resolution conversion unit 41 (S402). Further, the controller 10 acquires the humidity H detected by the humidity sensor SE2 (S404) and branches the process according to the humidity condition (S406). For example, if the threshold value for the detected humidity H is Ht, it can be determined that the first humidity condition is satisfied if the humidity H is the threshold value Ht or more, and if the humidity H is the threshold value Ht or more, it is higher than the first humidity condition. It can be determined that the high second humidity condition is satisfied.

When H ≧ Ht, which tends to cause color unevenness due to different “color-to-color distances”, the controller 10 converts the input color data DA1 into the output color data DA2 by referring to the LUT 1 in the color conversion unit 42 (S408). .. On the other hand, when H <Ht, which is unlikely to cause color unevenness due to the difference in "color-to-color distance", the controller 10 converts the input color data DA1 into the output color data DA2 by referring to the LUT 2 in the color conversion unit 42 ( S410).

When the humidity conditions different from the first humidity condition and the second humidity condition are satisfied, the controller 10 outputs the input color data DA1 with reference to the color conversion lookup table different from the LUT1 and the LUT2. It may be converted to DA2.

After the output color data DA2 is generated, the controller 10 converts the output color data DA2 into the recorded data DA3 in the halftone processing unit 43 (S412). After the recorded data DA3 is generated, the controller 10 generates a drive signal SG based on the recorded data DA3 in the signal transmission unit 44, outputs the drive signal SG to the drive circuit 62, drives the mechanism unit 50 (S414), and performs selective printing processing. To end.

As described above, the first printing in which the ink amount upper limit Dg and Dr are lower than the ink amount upper limit Db is performed under the first humidity condition in which color unevenness is likely to occur due to the difference in "color-to-color distance". Further, when the second humidity condition is such that color unevenness is unlikely to occur due to the difference in "color-to-color distance", the second printing is performed in which the ink amount upper limit Dg and Dr are set to the ink amount upper limit Db. Therefore, when the second humidity condition is satisfied, the upper limit of the amount of ink Dg and Dr does not decrease, so that the color reproducibility is improved. Of course, when the first humidity condition is satisfied, color unevenness due to the difference in "intercolor distance" is suppressed.

When the selection of "Media 1", which is likely to cause color unevenness due to the difference in "color-to-color distance", is accepted, and the first humidity condition is such that color unevenness is likely to occur due to the difference in "color-to-color distance". The first printing may be performed on the surface, and the second printing may be performed in other cases. Of course, if the selection of "Media 1" is accepted, and if it is the first temperature condition and the first humidity condition, the first print is performed, and in other cases, the second print is performed. You may go. In addition, when the selection of "Media 1", which tends to cause color unevenness due to different "color-to-color distance", is accepted, or under the first humidity condition where color unevenness tends to occur due to different "color-to-color distance". The first printing may be performed in some cases, and the second printing may be performed in other cases. Of course, if the selection of "Media 1" is accepted, or if it is the first temperature condition, or if it is the first humidity condition, the first print is performed, and in other cases, the second print is performed. May be printed.

(4) Modification example:
Various modifications of the present invention can be considered.
For example, the inkjet printer is not limited to a line printer, and may be a serial printer or the like that reciprocates a recording head in which a plurality of head chips are combined in a main scanning direction different from the sub scanning direction (paper feed direction).
Further, the output device is not limited to an inkjet printer that forms a two-dimensional printed image, and may be a three-dimensional printer or the like. The ink includes not only a liquid for expressing a color but also various liquids that impart some function such as a non-colored liquid that gives a glossy feeling. Therefore, the ink droplets include various droplets such as uncolored droplets.
The input color space is not limited to the RGB color space, and may be a CMY color space, a CMYK color space, or the like.
The above-mentioned processing can be changed as appropriate, such as changing the order. For example, in the selective printing process of FIG. 8, the process of S304 for acquiring the temperature T can be performed before the resolution conversion of S302.
Further, a printing apparatus that uses only LUT1 without using LUT2 is also included in the present technology.

The first nozzle row, the second nozzle row, the third nozzle row, and the fourth nozzle row described above can be fluidly fitted. For example, the first nozzle row can be fitted to the nozzle row 68M, the second nozzle row can be fitted to the nozzle row 68C, and the third nozzle row can be fitted to the nozzle row 68Y. In this case, the nozzle row 68C which is the second nozzle row and the nozzle row 68Y which is the third nozzle row are arranged in the alignment direction D1, and the nozzle row 68M (first nozzle row) in the relative movement direction D2. The distance between the nozzle row 68C (second nozzle row) is constant, and there are a plurality of distances between the nozzle row 68M (first nozzle row) and the nozzle row 68Y (third nozzle row) in the relative movement direction D2. There will be.
Of course, the arrangement of the nozzle rows with respect to the head tip is not limited to the arrangement shown in FIG. For example, the nozzle array of C and the nozzle array of Y may be arranged in the relative movement direction D2, or the nozzle array of M and the nozzle array of Y may be arranged in the relative movement direction D2. Further, the nozzle array of C and the nozzle array of M may be arranged in the alignment direction D1, or the nozzle array of M and the nozzle array of Y may be arranged in the alignment direction D1.

(5) Conclusion:
As described above, according to the present invention, there is provided a technique capable of suppressing color unevenness due to a plurality of distances between nozzle rows of different colors in the relative movement direction of the recording head in various aspects. be able to. Of course, the above-mentioned basic actions and effects can be obtained even with a technique consisting of only the constituent requirements according to the independent claims.
In addition, the configurations disclosed in the above-mentioned examples are mutually replaced or the combinations are changed, the known techniques and the configurations disclosed in the above-mentioned examples are mutually replaced or the combinations are changed. It is also possible to implement the above-mentioned configuration. The present invention also includes these configurations and the like.

1 ... Printing device, 2 ... Inverter printer, 10 ... Controller, 50 ... Mechanical unit, 53 ... Paper feed mechanism, 60 ... Recording head, 61 ... Head chip, 64 ... Nozzle, 67 ... Ink droplets, 68 ... Nozzle row, 73 ... Operation panel, 74 ... Output unit, 75 ... Input unit, 100 ... Host device, 500 ... Printed matter type selection screen, A1, A2 ... Non-ejection area, AL1 to AL6 ... Print area, D1 ... Arrangement direction, D2 ... Relative Moving direction, D21 ... Paper feed direction, D3 ... Width direction, DA1 ... Input color data, DA2 ... Output color data, DA3 ... Recorded data, DL, DL1-DL6 ... Line, DT0 ... Dot, Db, Dg, Dr ... Ink Upper limit of amount, IM1 ... Printed image, LUT1, LUT2 ... Color conversion lookup table, La ... Length of recording head in relative movement direction, Lb ... Length of head chip in relative movement direction, ME1 ... Printed matter, NL1 ... First One nozzle row, NL2 ... second nozzle row, NL3 ... third nozzle row, NL4 ... fourth nozzle row, Np ... nozzle pitch, SE1 ... temperature sensor, SE2 ... humidity sensor, U1 ... selective printing section, U2 ... printed matter Type selection section.

Claims (11)

A printing device in which the recording head and the printed matter move relative to each other in a relative moving direction different from the direction in which the nozzles in the nozzle row are arranged.
The recording head has two or more first nozzle rows that eject ink droplets of the first color, two or more second nozzle rows that eject ink droplets of the second color, and ink droplets of the third color. Has two or more third nozzle rows to eject
Of a plurality of nozzle rows that eject ink droplets on the same line along the relative movement direction,
The distance between the first nozzle row and the second nozzle row in the relative moving direction is constant.
There are a plurality of distances between the first nozzle row and the third nozzle row in the relative movement direction.
Regarding the upper limit of the amount of ink that can be ejected per unit area of the printed matter, the upper limit of the amount of ink obtained by combining the first nozzle row and the third nozzle row is the first nozzle row and the second nozzle row. A printing device that performs the first printing that is lower than the upper limit of the amount of ink combined with the nozzle row. The recording head includes a plurality of head chips having the first nozzle row, the second nozzle row, and the third nozzle row.
In the head chip, the first nozzle row and the second nozzle row are arranged in the relative movement direction, and one of the first nozzle row, the second nozzle row, and the third nozzle row are arranged. The printing apparatus according to claim 1, wherein the printing devices are arranged in the arrangement direction. The printing apparatus according to claim 2, wherein in the head chip, the third nozzle row and the fourth nozzle row for ejecting ink droplets of a fourth color are arranged in the relative movement direction. The printing apparatus according to claim 2 or 3, wherein the length of the recording head in the relative moving direction is three times the length of the head chip in the relative moving direction. The first color, the second color, and the third color are selected from cyan, magenta, and yellow, according to any one of claims 1 to 4. Printing equipment. The second upper limit of the amount of ink obtained by combining the first printing and the first nozzle row and the third nozzle row is the upper limit of the ink amount obtained by combining the first nozzle row and the second nozzle row. The printing apparatus according to any one of claims 1 to 5, further comprising a selective printing unit that selectively performs printing and a plurality of printing including printing. Equipped with a printed matter type selection unit that accepts the selection of the printed matter type used for printing.
The selective printing unit performs the first printing when the type of the printed matter for which the selection is accepted is the first type, and when the type of the printed matter for which the selection is accepted is the second type. The printing apparatus according to claim 6, wherein the second printing is performed. Equipped with a temperature sensor that detects temperature
The selective printing unit performs the first printing when the temperature detected by the temperature sensor satisfies the first temperature condition, and when the second temperature condition higher than the first temperature condition is satisfied. The printing apparatus according to claim 6 or 7, wherein the second printing is performed. Equipped with a humidity sensor that detects humidity
The selective printing unit performs the first printing when the humidity detected by the humidity sensor satisfies the first humidity condition, and when the second humidity condition lower than the first humidity condition is satisfied. The printing apparatus according to any one of claims 6 to 8, which performs the second printing. The selective printing unit is
When performing the first printing, the upper limit of the amount of ink obtained by combining the first nozzle row and the third nozzle row according to the first correspondence relationship from the input color is the same as the first nozzle row and the second nozzle row. Convert the ink to the output color used so that it is lower than the upper limit of the amount of ink
When performing the second printing, the upper limit of the ink amount of the first nozzle row and the third nozzle row combined according to the second correspondence relationship from the input color is the sum of the first nozzle row and the second nozzle row. The printing apparatus according to any one of claims 6 to 9, wherein the ink is converted into an output color to be used so as to be an upper limit of the amount of ink. This is a printing method in which the recording head and the printed matter move relative to each other in a relative moving direction different from the direction in which the nozzles in the nozzle row are arranged.
The recording head has two or more first nozzle rows that eject ink droplets of the first color, two or more second nozzle rows that eject ink droplets of the second color, and ink droplets of the third color. Has two or more third nozzle rows to eject
Of a plurality of nozzle rows that eject ink droplets on the same line along the relative movement direction,
The distance between the first nozzle row and the second nozzle row in the relative moving direction is constant.
There are a plurality of distances between the first nozzle row and the third nozzle row in the relative movement direction.
Regarding the upper limit of the amount of ink that can be ejected per unit area of the printed matter, the upper limit of the amount of ink obtained by combining the first nozzle row and the third nozzle row is the first nozzle row and the second nozzle row. A printing method that performs the first printing that is lower than the upper limit of the amount of ink combined with the nozzle row.

Images